#include <bits/stdc++.h>

using namespace std;

class Solution
{
public:
    vector<vector<int>> construct2DArray(vector<int> &original, int m, int n)
    {
        vector<vector<int>> ret;
        int count = 0;
        if (original.size() != m * n)
            return ret;
        for (int i = 0; i < m; ++i)
        {
            vector<int> tmp;
            for (int j = 0; j < n; ++j)
            {
                tmp.push_back(original[count++]);
            }
            ret.push_back(tmp);
        }
        return ret;
    }
};